/* This code is based on public domain code from Wei Dai's Crypto++ library. */



#define rotl_u32(x, n) (((x) << (n)) | ((x) >> (32 - (n))))

#define rotr_u32(x, n) (((x) >> (n)) | ((x) << (32 - (n))))



#include "sha256.h"



/* define it for speed optimization */

/* #define _SHA256_UNROLL */

/* #define _SHA256_UNROLL2 */



void Sha256_Init(CSha256 *p)

{

  p->state[0] = 0x6a09e667;

  p->state[1] = 0xbb67ae85;

  p->state[2] = 0x3c6ef372;

  p->state[3] = 0xa54ff53a;

  p->state[4] = 0x510e527f;

  p->state[5] = 0x9b05688c;

  p->state[6] = 0x1f83d9ab;

  p->state[7] = 0x5be0cd19;

  p->count = 0;

}



#define S0(x) (rotr_u32(x, 2) ^ rotr_u32(x,13) ^ rotr_u32(x, 22))

#define S1(x) (rotr_u32(x, 6) ^ rotr_u32(x,11) ^ rotr_u32(x, 25))

#define s0(x) (rotr_u32(x, 7) ^ rotr_u32(x,18) ^ (x >> 3))

#define s1(x) (rotr_u32(x,17) ^ rotr_u32(x,19) ^ (x >> 10))



#define blk0(i) (W[i] = data[i])

#define blk2(i) (W[i&15] += s1(W[(i-2)&15]) + W[(i-7)&15] + s0(W[(i-15)&15]))



#define Ch(x,y,z) (z^(x&(y^z)))

#define Maj(x,y,z) ((x&y)|(z&(x|y)))



#define a(i) T[(0-(i))&7]

#define b(i) T[(1-(i))&7]

#define c(i) T[(2-(i))&7]

#define d(i) T[(3-(i))&7]

#define e(i) T[(4-(i))&7]

#define f(i) T[(5-(i))&7]

#define g(i) T[(6-(i))&7]

#define h(i) T[(7-(i))&7]





#ifdef _SHA256_UNROLL2



#define R(a,b,c,d,e,f,g,h, i) h += S1(e) + Ch(e,f,g) + K[i+j] + (j?blk2(i):blk0(i));\
  d += h; h += S0(a) + Maj(a, b, c)



#define RX_8(i) \
  R(a,b,c,d,e,f,g,h, i); \
  R(h,a,b,c,d,e,f,g, i+1); \
  R(g,h,a,b,c,d,e,f, i+2); \
  R(f,g,h,a,b,c,d,e, i+3); \
  R(e,f,g,h,a,b,c,d, i+4); \
  R(d,e,f,g,h,a,b,c, i+5); \
  R(c,d,e,f,g,h,a,b, i+6); \
  R(b,c,d,e,f,g,h,a, i+7)



#else



#define R(i) h(i) += S1(e(i)) + Ch(e(i),f(i),g(i)) + K[i+j] + (j?blk2(i):blk0(i));\
d(i) += h(i); h(i) += S0(a(i)) + Maj(a(i), b(i), c(i))



#ifdef _SHA256_UNROLL



#define RX_8(i) R(i+0); R(i+1); R(i+2); R(i+3); R(i+4); R(i+5); R(i+6); R(i+7);



#endif



#endif



static const uint32_t K[64] = {

  0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,

  0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,

  0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,

  0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,

  0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,

  0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,

  0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,

  0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,

  0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,

  0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,

  0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,

  0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,

  0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,

  0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,

  0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,

  0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2

};



static void Sha256_Transform(uint32_t *state, const uint32_t *data)

{

  uint32_t W[16];

  unsigned j;

  #ifdef _SHA256_UNROLL2

  uint32_t a,b,c,d,e,f,g,h;

  a = state[0];

  b = state[1];

  c = state[2];

  d = state[3];

  e = state[4];

  f = state[5];

  g = state[6];

  h = state[7];

  #else

  uint32_t T[8];

  for (j = 0; j < 8; j++)

    T[j] = state[j];

  #endif



  for (j = 0; j < 64; j += 16)

  {

    #if defined(_SHA256_UNROLL) || defined(_SHA256_UNROLL2)

    RX_8(0); RX_8(8);

    #else

    unsigned i;

    for (i = 0; i < 16; i++) { R(i); }

    #endif

  }



  #ifdef _SHA256_UNROLL2

  state[0] += a;

  state[1] += b;

  state[2] += c;

  state[3] += d;

  state[4] += e;

  state[5] += f;

  state[6] += g;

  state[7] += h;

  #else

  for (j = 0; j < 8; j++)

    state[j] += T[j];

  #endif

  

  /* Wipe variables */

  /* memset(W, 0, sizeof(W)); */

  /* memset(T, 0, sizeof(T)); */

}



#undef S0

#undef S1

#undef s0

#undef s1



static void Sha256_WriteByteBlock(CSha256 *p)

{

  uint32_t data32[16];

  unsigned i;

  for (i = 0; i < 16; i++)

    data32[i] =

      ((uint32_t)(p->buffer[i * 4    ]) << 24) +

      ((uint32_t)(p->buffer[i * 4 + 1]) << 16) +

      ((uint32_t)(p->buffer[i * 4 + 2]) <<  8) +

      ((uint32_t)(p->buffer[i * 4 + 3]));

  Sha256_Transform(p->state, data32);

}



void Sha256_Update(CSha256 *p, const uint8_t *data, size_t size)

{

  uint32_t curBufferPos = (uint32_t)p->count & 0x3F;

  while (size > 0)

  {

    p->buffer[curBufferPos++] = *data++;

    p->count++;

    size--;

    if (curBufferPos == 64)

    {

      curBufferPos = 0;

      Sha256_WriteByteBlock(p);

    }

  }

}



void Sha256_Final(CSha256 *p, uint8_t *digest)

{

  uint64_t lenInBits = (p->count << 3);

  uint32_t curBufferPos = (uint32_t)p->count & 0x3F;

  unsigned i;

  p->buffer[curBufferPos++] = 0x80;

  while (curBufferPos != (64 - 8))

  {

    curBufferPos &= 0x3F;

    if (curBufferPos == 0)

      Sha256_WriteByteBlock(p);

    p->buffer[curBufferPos++] = 0;

  }

  for (i = 0; i < 8; i++)

  {

    p->buffer[curBufferPos++] = (uint8_t)(lenInBits >> 56);

    lenInBits <<= 8;

  }

  Sha256_WriteByteBlock(p);



  for (i = 0; i < 8; i++)

  {

    *digest++ = (uint8_t)(p->state[i] >> 24);

    *digest++ = (uint8_t)(p->state[i] >> 16);

    *digest++ = (uint8_t)(p->state[i] >> 8);

    *digest++ = (uint8_t)(p->state[i]);

  }

  Sha256_Init(p);

}

